1. Field of the Invention
The present invention relates to a system and device for holding a bit for a tool, the bit to be disassembled and/or re-assembled when held. The invention also relates to a method of disassembling and/or re-assembling the bit.
2. Description of the Related Art
A router is a tool, especially used in the woodworking industry, used for milling out (hollow out) an area in the face of a piece of material (workpiece). Usually the material is wood or metal, but applying the router to other types of materials is also possible. There are several types of routers. Nowadays, most common types are spindle type routers (spindle routers), where a router bit is mounted onto a rotatable spindle of an electric motor.
A typical router set-up includes a frame for supporting the router table. The piece of material to be machined is supported by the table. Also the router is mounted to the support table. The table has an opening through which a bit protrudes for machining the material. Different bit sizes and shapes can be used, and the bit is easily exchangeable. The bit is engaged by a collet provided with a clamping mechanism including a number of clamps or jaws. The collet is part of a rotatable spindle that is connected to a motor drive for rotation. The router collet (and router bit mounted in the mouth of the collet) can be rotated around an axis perpendicular to the router table. Sometimes the collet may be able to move with respect to the table, for example, along the axis of rotation by a depth adjustment tool. In this case, the shape of the cut that is created is determined by the size and shape of the bit (cutter) held in the collet and the height of the bit relative to the upper surface of the router table.
One of the important variables determining the router's work is the shape of the router bit (the cutter). A large variety of different router bit shapes is on the market nowadays, allowing an almost indefinite shape to be routed to the workpiece. A part of the router bits is formed by the so-called stacked router bits. Typically, a stacked router bits consist of a central shaft (the shank, usually ½ inch diameter, but other diameters are possible as well), with a threaded top end on which are mounted one or more removable bit elements, including (but not limited to) disc shaped cutters, (ball) bearings for guidance and/or various shims or spacers. To keep the stack of bit elements cutters and spacers firmly on the shank, an end nut or similar device is tightened on top of the shank.
Adding or removing bit elements such as spacers or shims in between other bit elements such as the cutters may be required to modify the thickness of wood removed in the routing process or the depth of cut in case of a ball bearing diameter change. Cutters may have to be substituted by other cutters, for instance differently shaped cutters, or by other types of bit elements. The operation of loosening the nut, removing the bit elements, replacing them, if needed, by other bit elements and re-tightening the nut on the shank is generally done with the router bit mounted in the router machine itself, more specifically in the router collet.
The operation of disassembling and/or re-assembling stacked router bits while keeping the router bits chucked into the router is cumbersome for various reasons. First of all, unless the router itself is securely held, for instance in a base element such as a router table, the router, in turn, will require to be secured to prevent it from turning when applying torque to unscrew or refasten the end nut. This can be done if the router is held in the router table, but that prevents the router table to be set up for alternative operations. Moreover, when the operation is performed in case the stacked router bit is clamped by the collet of the router, small parts, such as spacers, washers etc. may fall into the router motor housing. Furthermore, during the time interval wherein the router bit is chucked in the router collet for disassembling or re-assembling it, the router cannot be used for other purposes, such as milling another workpiece. A further drawback is that the visibility is less than ideal, because the router collet generally cannot protrude far enough above the router table to allow a full and unencumbered view of the operation.
Alternatively, the stacked router bits could be held by a clamping element such as a hand plier or a steel bench vise. Generally, however, these clamping elements are less capable of resisting the considerable torque, required to unscrew and re-fasten the end nut. Besides, these clamping elements would engage directly on the router bit shank in such a manner that the risk is present to destroy the integrity of the bit and to render it useless or even dangerous for further usage. Consequently, there is currently no method to hold the router bit successfully other than in the router collet itself.